代码随想录算法训练营第三十九天 | 不同路径、不同路径 II

● 今日学习的文章链接和视频链接

题目62.不同路径
题目63. 不同路径 II

● 看到题目的第一想法

找路径

● 看完代码随想录之后的想法

EZ

● 实现过程中遇到哪些困难

和之前机器人的实验很像，写的快

● 解题代码

1. 点击查看代码

   class Solution {
       public int uniquePaths(int m, int n) {
   		int[][] dp = new int[m][n];
   		for (int i = 0; i < n; i++) {
   			dp[0][i] = 1;
   		}
   		for (int i = 0; i < m; i++) {
   			dp[i][0] = 1;
   		}
   		for (int i = 1; i < m; i++) {
   			for (int j = 1; j < n; j++) {
   				dp[i][j] = dp[i-1][j] + dp[i][j-1];
   			}
   		}
   		return dp[m - 1][n - 1];
       }
   }
   

2. 点击查看代码

   class Solution {
       public int uniquePathsWithObstacles(int[][] obstacleGrid) {
   		int m = obstacleGrid.length;
   		int n = obstacleGrid[0].length;
   		int flag = 0;
   		int[][] dp = new int[m][n];
   		if(obstacleGrid[m - 1][n - 1] == 1){
   			return 0;
   		}
   		for (int i = 0; i < n; i++) {
   			if(obstacleGrid[0][i] == 1){
   				flag = 1;
   			}
   			if(flag == 0){
   				dp[0][i] = 1;
   			}else{
   				dp[0][i] = 0;
   			}
   		}
   		flag = 0;
   		for (int i = 0; i < m; i++) {
   			if(obstacleGrid[i][0] == 1){
   				flag = 1;
   			}
   			if(flag == 0){
   				dp[i][0] = 1;
   			}else{
   				dp[i][0] = 0;
   			}
   		}
   		flag = 0;
   		for (int i = 1; i < m; i++) {
   			for (int j = 1; j < n; j++) {
   				if(obstacleGrid[i-1][j] == 1 && obstacleGrid[i][j-1] == 1){
   					dp[i][j] = 0;
   				}
   				if(obstacleGrid[i-1][j] == 1 && obstacleGrid[i][j-1] == 0){
   					dp[i][j] = dp[i][j-1];
   				}
   				if(obstacleGrid[i-1][j] == 0 && obstacleGrid[i][j-1] == 1){
   					dp[i][j] = dp[i-1][j];
   				}
   				if(obstacleGrid[i-1][j] == 0 && obstacleGrid[i][j-1] == 0){
   					dp[i][j] = dp[i-1][j] + dp[i][j-1];
   				}
   			}
   		}
   		return dp[m - 1][n - 1];
       }
   
   }
   

● 今日收获，学习时长

今日收获：学习了DP找路径
学习时长：1h